1. Field of the Invention
The present invention relates to a hybrid drive and a method for starting a hybrid drive.
2. Description of Related Art
An impulse start method and an impulse start device for an internal combustion engine are known from published German DE 199 56 384. According to the impulse start method described in DE 199 56 384, a flywheel mass is accelerated in a rotationally driven manner during an acceleration phase and the flywheel mass is subsequently coupled with a rotationally mounted shaft, preferably the crankshaft of the internal combustion engine, during a coupling phase for the purpose of transmitting torque. During the cranking phase and/or the coupling phase, the speed progression of the flywheel mass is evaluated, and this evaluation is used to determine whether the internal combustion engine may be successfully started. If a successful start is not to be expected, the internal combustion engine is placed via the shaft in an operating position which is favorable for a subsequent second start attempt. According to the impulse start method known from DE 199 56 384, the gradient of the speed progression of the flywheel mass is used during the cranking phase for the evaluation and, if the gradient is too low, the coupling phase is initiated.
In vehicles currently on the market having hybrid drives which include an internal combustion engine and at least one electric drive, there is no way for the driver to start the vehicle if the high-voltage battery is discharged. This is a highly unsatisfactory situation.